Attaching edges with dissimilar vertex counts
This is what I'd recommend:

There are no triangles, and no 6 poles.  There are, however, 3 poles and 5 poles.
Notice another thing: your left attempt has degenerate quads, quads with 3 collinear vertices.  Triangulation can create zero-area faces which wreak havoc on the interpolation of smooth-shaded normals.  It's easily enough fixed, just wanted to make sure you were thinking of it.
There are a number of issues with vertex connections like this.  Undesirable poles cannot be completely eliminated.  There is no way to connect an odd number of verts to an even number of verts without making triangles.  For character animation, you frequently screw up your edge flow or topology chosen to hold volume at joints, and those are more important than your strict vertex count-- you're better off adding or deleting edge loops than you are trying to use joining techniques.
The way to work with the poles is to minimize their impact.  Place them on the most planar part of the mesh that you can-- even a thousand=pole is fine when all of its neighbor faces are coplanar!  You don't have to drop the whole 2:1 over a single edge loop; you can use multiple edge loops, dropping 2 or 4 verts each one, so that you can place your poles more carefully.